Ultrasound reveals cause of carpal tunnel syndrome

Ultrasound reveals cause of carpal tunnel syndrome

November 07, 2003

When it comes to carpal tunnel syndrome, ultrasound's diagnostic accuracy offers an alternative to distressing electrophysiological studies, according to researchers in Egypt.

The investigative team from Ain Shams University in Cairo evaluated 78 patients with carpal tunnel syndrome and 78 control subjects. Both groups underwent ultrasound of the wrists and a self-examination assessment. Carpal tunnel syndrome patients also underwent electromyography (EMG).

Although all three tests provided similar results, researchers found that only ultrasound could determine the exact cause of symptoms. They presented their study at the annual meeting of the American College of Rheumatology in October in Orlando.

Ultrasound measured the cross-sectional area of the median nerve. A measurement up to 10 mm2 for the mean cross-sectional area of the median nerve represented normal ultrasound values. Between 10 and 13.03 mm2 indicated mild tenosynovitis, and between 13.03 and 15.02 mm2 signaled a moderate condition. Above that limit was termed severe.

"It is time to say farewell to nerve conduction studies for assessment of patients suffering from carpal tunnel syndrome," said principal investigator Dr. Yasser M.A. El Miedany, an associate professor of rheumatology and rehabilitation at Ain Shams.

In addition to being noninvasive, accurate, and quick, ultrasound can define the cause of nerve compression. It confirmed tenosynovitis as the primary cause of carpal tunnel syndrome in 16 patients, El Miedany said.

Ultrasound correlated significantly with the other tests in the study (p

"Ultrasound examination should be strongly considered as a new alternative diagnostic modality," he said.

Primary-care physicians in the U.S. refer carpal tunnel syndrome patients to a number of specialists — including radiologists — to confirm their clinical diagnosis. Most use EMG to determine nerve conduction delay through the carpal tunnel. The procedure involves electric stimulation, which is often uncomfortable and even painful.

Others, however, favor ultrasound, said Dr. Levon Nazarian, an associate professor of radiology at Thomas Jefferson University. The Ain Shams and other studies reinforce imagers' drive to provide patients with a convenient, noninvasive, and painless diagnosis.

"If we had a method that could reduce or eliminate the need for EMG, the patients would love it," he said.